Comments which come in within the week of a post tend to be focused on the post's content. I absolutely welcome these and enjoy the dialogue which may result. The feedback you provide gives me insight into what you feel is helpful or lets me know when a post speaks to you.
Comments which come long after the fact tend to fall into two categories. First, there are the comments which express appreciation for the post. Second, there are the comments which purport to have a cure for dementia and link out to a sketchy site. The first will be approved for your viewing. The second will be deleted after I check out the claims and the links provided.
While I was away, a comment came in on a post from 2013. It had quite the claim of a miracle cure and the contact information for the "healer" lead to some pretty questionable material. The comment was deleted. In my searching, I found the exact same comment had been posted to other sites. Someone was spamming a number of unrelated sites with the same malarkey.
I hope that one day, there will be a real cure or a viable prevention which can give us hope. In the meantime, I do feel an obligation to screen the comments.